JPS6178461A - Coating method and apparatus therefor - Google Patents

Abstract

PURPOSE:To enhance the film quality of a coating start part, in an engaging mount type vacuum slide bead coating apparatus, by engaging a slide hopper with the housing in the side of a coating roller in an inserted state before flowing in the open air from an upper opening. CONSTITUTION:When a coating roller side C and a slide hopper side H are engaged in an inserted state, a housing 3' having an opening 33 with an upward width B is formed so as to be surrounded by the surface of the web 11 trained around a roller 1, an enclosure 31 and a slide hopper 2. At this time, the open air is flowed into the housing 3' only from the opening 33 by the seal effect of the front and side seal plates 311, 312 of the enclosure 31. As engagement and insertion advance, the opening width B becomes narrow and, when said width B reaches about 10cm under a usual vacuum condition, the liquid sump 41 generated along a lip part 31 begins to be shaven off by the high speed air stream through the opening 33 to form a condition near to the state of a coating layer forming a bead in a coating steady state.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a coating apparatus and method used in the production of photographic materials, and more specifically to a so-called slide bead coating apparatus and method.

(Prior Art) Photographic materials generally contain hydrophilic colloids (e.g. gelatin) containing additives that suspend the halogenated particles and/or mask photographic properties and productivity, on polyethylene terephthalate or baryta paper. It is manufactured by continuously coating and drying a flexible long web.

The dip method, double roll method, air doctor method, etc. were initially used as a method for disposing the photographic layers constituting the photographic material on the web, and the curtain coating method and slide bead method were used in response to the demand for simultaneous multi-node high-speed coating. Coating methods and the like have been developed, and the slide bead coating method has now become the mainstream.

Regarding the slide bead coating method, US Pat.
81,294-q, 2,761,419, 2,7
No. 61,791 and British Patent No. 837,095.

As described in the above patent, the slide bead coating method uses one or more coating liquids fC coating feeder (slide hopper).
Extrude as a continuous wide rib from the slit provided in the N41') of the extended surface (slide surface)
A single layer or a top layer ribbon of the coating liquid is passed over the web surface running close to the surface of the web running in close proximity to the coating liquid to form a bead. A single coating or a multilayer coating is applied on the web by matching the running speed. Incidentally, the running web is generally stretched over an application roller provided close to the lip portion.

Therefore, in the slide bead coating method as described above, it is essential that the coating liquid supply amount and web running speed [(11! Cloth speed) be perfectly matched, but in addition, there is The shape stability of the bead formed by the coating liquid ribbon that is passed to the surface has a large effect on the uniformity and dry finish of the coating film.

For example, if the bead follows or retards in the running direction of the web, that is, if the bead vibrates in the longitudinal direction of the web, it will simply cause horizontal stripes (rib-like unevenness), coating breakage, and furthermore, the vibration will cause the coating to sag at the bead position. If mixing occurs between liquid layers, uneven spots and vertical stripes will occur.

These disadvantages cannot be avoided unless the bead itself has an active self-restoring force for stabilizing the bead shape.

In U.S. Clock No. 2,681,294, a vacuum chamber was added to stabilize the beads by suctioning the beads by frozen soil in the opposite direction to the running direction of the web.

However, the air seal plate in the decompression chamber can be safely kept non-contact with the traveling web while still achieving a sufficient degree of decompression.
One hour! In order to maintain J, there is always a deep I! 1: Requires special care and is a problem in the process.

Furthermore, in this type of coating method, when the coating liquid starts to be applied to the web, even if the coating liquid comes into contact with the running web, the coating liquid is not applied to the web immediately, but after passing through a slight guidance period. be done.

Moreover, at the point where the coating liquid begins to be applied to the web, the coating film becomes thicker than in other parts. This thickly painted part is
Even though it is only a small part of the overall process, it is necessary to make the wire transfer process longer.

In addition, if this thickly coated area is insufficiently dried, a portion of the undried coating may adhere to the reversing roller etc. after the drying process, contaminating the process or disturbing the coating surface of the trowel. becomes.

Various attempts have been made to address the above problem. For example, in U.S. Pat. No. 3,220,877, in a coating mode using a slide bead, prior to passing the bead from the lip to the web, , discloses a method for eliminating a thick film at the start of coating by increasing the degree of vacuum in a vacuum chamber. However, when the decompression level is completely exhausted or when returning to the normal decompression level,
The bead part becomes unstable for a while, and coating streaks are likely to occur.In high speed and/or thin film coating, the instability increases and does not necessarily give satisfactory results.

Furthermore, as shown in Japanese Patent Publication No. 57-36025, for example, there is a method in which the web coating is improved by steam spraying or the like so that the coating can be applied quickly. However, with this method, adjustment of the amount of steam is indispensable, and great care must be taken in fine adjustment. That is, if the amount of steam is too small, there will be no effect, and if it is too large, undried areas will occur. Furthermore, as shown in Japanese Patent Application Laid-Open No. 50-92328, there is a web in which the part where coating should start is roughened to make it easier to coat, but this does not require pre-process equipment etc. to roughen the surface. Reduce man-hours.

On the other hand, requests for the distribution of business luck thin films are becoming more and more popular, and along with this, the demand for distribution of business luck thin films is increasing. A cloth drying device that is less likely to cause damage, has less loss due to thick film, is easy to operate, and is 18 mm thick is reliable.

(Problems to be Solved by the Invention) In a coating method using a slide bead coating device I equipped with a vacuum chamber, a thick film portion that occurs at the coating start portion of the web causes a decrease in product yield. The fact that the drying load that should not have been originally required is forced to occur due to the LIE and m parts that are historically discarded as product loss due to one problem is a major cost problem.

In addition, the bead shape, which has a large effect on the uniformity of the coating film and the drying finish, requires adjustment of the degree of vacuum at the initial stage of coating, and high precision adjustment of the web surface stretched over the glue cloth and the air/hole in the vacuum chamber. Stabilizing by adjusting the gap is a difficult and difficult process, and requires a weight device that is reliable, easy to operate, and capable of quick stabilization.

(Means for solving the problem) Looking at the state of the coating liquid ribbon on the slide surface during slide bead coating, it appears that the coating is applied at the lip before forming a bead between it and the web. lE IJ bongs have a single raised liquid reservoir along the lip, which varies slightly depending on the liquid properties and flow rate, but this liquid reservoir υ mainly corresponds to the thick film part at the beginning of coating. I was able to figure out what was going on.

As a way to deal with the thick film caused by this rL accumulation, it is obviously more advantageous to treat it before coating than after coating.6! :l.

It was discovered that the liquid pool can be efficiently scraped off by blowing an air stream before bead formation (as a method of treatment), and that the modification of the coating equipment associated with this can be kept to a small extent.

In addition, the stability of the bead, which has a great influence on the quality of the coated product, depends on the aerosol gap and its accuracy between the web surface stretched over the coating roller, and if the gap is wide, the inflowing air will In many cases, turbulence occurs in the air flow in the decompression base circle, and if the precision of the gap is poor in the direction of the core of the decompression chamber, the air flow on the interior wall will be biased, making the bead unstable.

As described above, it is possible to precisely adjust the vacuum specifications necessary to improve the coated product's strength by modifying the coating apparatus to provide a convenient form.

In other words, the n-th coating machine is constructed by installing the grinding stone roller that stretches the web and the slide hopper side that supplies the coating liquid in the form of a ribbon. At the fitting type vacuum type slide bead coating device, which forms a bead between the lip of the slide hopper and applies the coating liquid. .

On the coating roller side, the side facing the slide hopper is open, and the other side is closed to the hook cloth roller for 15 seconds.
- By fixing a housing which is spaced apart and close to each other and is open at the top and into which the slide hopper can be inserted, and the slide hopper and the housing are inserted until the coating liquid forms a bead. This is a coating method characterized by allowing the substantial outside air to flow in only through an upwardly opened opening that becomes narrow as the demon's energy advances.
The above-mentioned problems can be solved by changing the J method according to the transfer method and using the 7b decomposition device.

In the present invention, the substantial inflow of outside air into the decompression chamber refers to the seal gap allowed between the optical surface of the web stretched over the grinding stone roller and the gap between the housing and the slide hopper insertion surface. This refers to the degree to which the inflow of outside air from etc. can be ignored in practice.

Next, the present invention will be explained using figures.

FIG. 1 is a vertical sectional view of an embodiment of the coating apparatus of the present invention. The state shown in the same figure is the state before the application roller side C and the slide hopper side are inserted into each other and can be operated normally as a '111 stone device. Not configured yet.

On the coating roller side C in the same figure, 1 is a coating roller that stretches the web 11, and on the slide hopper side H, 2 is a coating liquid that is applied in a single layer or in layers and is cast onto the slide surface 20 in the form of a ribbon. This is a slide hopper for feeding. The slide hopper is equipped with a coating liquid reservoir 22, a nozzle 23, a slit 24, an outflow machine #425, and other equipment necessary for the slide bead coating device for each coating liquid. Further, 26 is a coating liquid recovery chamber which is used harshly when collecting the Slide Hofno (-2).

Reference numeral 21 denotes a lip portion at the end of the slide motherboard, and a bead is formed between the lip portion and the web 11 when used as a seat cloth.

Next, 31 is a housing fixed to the application roller @C. 311 marks the entry of the web 11 into the housing 31;
1 (front) front seal plate, 321 and 312
'(not shown) is a side seal plate provided on the axial side (side) 1II11@ of the vehicle height roller l on which the nib 11 is stretched. 32 is an exhaust pipe, and P is used for evacuation, for example, a decompression fan. In addition to the front and side seal plates described above, it is preferable to employ labyrinth seals on the front and/or site for outside air.

Reference numeral 4 denotes a single layer or a laminated coating liquid layer in which the slide motherboard of the coating liquid extruded from the slit 24 or the like is cast in a ribbon shape, and in the illustrated example, it ultimately forms three layers. There is.

The coating liquid 1!14Vi formed in the ribbon shape and cast on the slide surface 20, in the case of free falling under electric power, is the lip part 2.
1, a liquid puddle 41 is formed along the rig line,
It flows down the front face 27 of the slide hopper.

In the method of the present invention, in the state IK shown in FIG. 1 with the coating roller side C and the slide hopper 111H on board, jt
Various preparations can be made in detail to bring about excessive coating conditions such as adjustment of the seal gap under the continuous condition, regulation of the bead gap between the web and the lip, and reduced pressure conditions.

Next, FIG. 2 shows a state in which the coating roller side C and the slide hopper side H are being inserted. The mechanism on the slide hob par side H is shown in a simplified manner.

The path of movement of the two for fitting and insertion is arbitrary, and if the housing 31 on the application roller side C is fixed, the path on the slide hopper side H is horizontal, vertical, diagonal, or a combination thereof. It is only necessary to reach the fitted state of the carp H by doing this. whistle 2
The figure shows an example of g4 horizontal movement.

'1' ft, the fitting surfaces of the fallen cloth roller side C and the slide hopper side (for example, the inside of the housing 31 and the slide hopper 2
The 1118th surface and the bottom surface from that side, etc.) are fitted together, and airtightness is provided by the sliding finish of the surfaces or by auxiliary means such as Pubking.In the illustrated example, Pubking 32aX b , cX d, etc. are used in one place.

When the vehicle height roller side C and the slide hopper side H are fitted, the surface of the sea urchin 11J stretched over the coating row 21 and the housing 31
Then, the slide hopper 2 was used as a sub-tube and turned upward for plowing. d
An opening 33 (front piece of the slope pressure vine) 3' is formed to allow outside air (in practical terms, air) d, the housing, and the front and side seal plates 311 and 7 of the side seal plates 311 and 312. As a result, the person is transferred to the housing 3' only through the opening 33.

As the fitting becomes looser, the opening width B of the opening 33 becomes narrower, and the speed of outside air flowing in from the opening 33 becomes faster. The incoming airflow only begins to scrape the g pool 41 that had formed, and the liquid puddles v and 41' have a slight rise.
And then I! [The coating liquid layer approaches the state of forming a bead under normal conditions.

Next, Fig. 3 shows the coating roller IC and the slide hopper [H
The figure shows the state in which it is fully fitted and has the proper coating function and decompression function.

The housing 3' (predecessor of the decompression chamber) having the opening 33 is constituted by the regular decompression chamber 3, and under the normal operating condition of the decompression chamber, the lip portion 21 at the end of the sliding surface 20 and the running web 11 are connected to each other. A bead 42 in a steady state is formed in between, and the ribbon-shaped coating liquid layer 4 that casts the slide motherboard passes through the bead 42 and forms an I! on the web 11. A steady coating state is entered in which the I film 5 is coated.

# @ Pressure level is θ ~ 100 tax ~, preferably huge = 70 nod ~, bead gap is 10 ~ 100 at the above pressure reduction degree
0 μm, preferably 10 to 300 μm.

As mentioned above, the seal gap and the bead gap, which have a huge effect on the stability of the bead 42 which affects the coating quality, are precisely adjusted in advance to suit the optimum coating conditions without any omissions and easily. The liquid pool 41 in the lip part 21, which causes a thick film part at the starting part, can be removed in advance to make it convenient for coating. .

(Effect of the invention) Thickness 11 that always occurred at the coating start part of the web!
The i1 portion becomes extremely light and small, resulting in an improvement in product yield and a significant reduction in drying load.

Furthermore, since the bead width and other coating requirements are set with high precision, the stability of the bead is well utilized and coating failures such as coating unevenness are greatly minimized.

Furthermore, from the perspective of workability, once the speed 11@ is adjusted, there is no need to adjust it again when replacing the hopper, etc.
In addition, changes in the seal gap due to thermal strain are absorbed by the airtightness auxiliary means, such as a seal packing, and workability is greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of an actual embodiment of the coating device of the present invention in an uninserted state. Fig. g2 is a vertical sectional view of the product during insertion, and Fig. 3 is a vertical cross-sectional view of the product in a low iron state. C... Application roller, H... Slide hopper side 1... Application roller 11... Web 2...
Slide hopper 20...Sliding surface 21...Ripgu part 3...Decompression chamber 31...Plow body 311 and 312...Seal plate 4...Coating liquid layer 41...PIL reservoir 42...・Peed 5...Painting agent Patent attorney No. 1) Parent-in-law Figure 2

Claims (2)

[Claims] (1) The coating function is configured by fitting the coating roller side that stretches the web with the slide hopper side that supplies the coating liquid in the form of a ribbon, and the web surface stretched on the coating roller and the slide hopper side. In a fitted type vacuum type slide bead coating device that forms a bead between the lip of the roller and applies the coating liquid, the side facing the slide hopper is open on the side of the coating roller, and the other side faces are exposed to the coating roller. A housing that is close to each other with a seal gap in between and that is open at the top and that can be inserted into the slide hopper is fixed, and the slide hopper and the housing are inserted until the coating liquid forms a bead. A coating method characterized in that a substantial amount of outside air is allowed to flow in only through an upwardly opened opening that is created by this process and becomes narrower as the fitting progresses. (2) By fitting the coating roller side that stretches the web with the slide hopper side that supplies the coating liquid in the form of a ribbon, it is possible to create a space between the web surface stretched on the coating roller and the lip of the slide hopper. In a fitted type reduced pressure type slide bead coating device that forms a bead on the surface and applies a coating liquid, the side surface on the slide hopper side is open to the coating roller side, and the other side surfaces are close to the coating roller with a seal interval between them. A housing that is open at the top and that can be inserted into the slide hopper is fixed, and the slide hopper and the housing are inserted until the coating liquid forms a bead. A coating device characterized in that a substantial amount of outside air is allowed to flow in only through an upwardly opened opening which becomes narrower as the coating device is advanced.